Firms increasingly use external vendors to provide training for their employees. And because trust has been found to be essential in successful interfirm relationships, this study identified a number of factors thought to be associated with both self-interested trust and socially oriented trust between firms and their training suppliers. Using data obtained from 323 organizations, regression analysis suggests that idiosyncratic training, program uncertainty, vendor dependency, contractual specificity, and communication accuracy and frequency were significantly related to higher levels of trust in outsourcing relationships.